Citando :

RF FILTER UNIT (Fig.4)
The received signal is connected directly into the RF filter unit (compartment 1 of the turret assembly). The filter unit contains eight bandpass filters with pass bands as follows:

FL1 0 to 2MHz
FL2 2 to 3MHz
F13 3 to 4MHz
FL4 4 to 6MHz
FL5 6 to 9MHz
FL6 9 to 14MHz
FL7 14 to 21MHz
FL8 21 to 30MHz

When the MEGAHERTZ control is set to the MHz of the required frequency, the filter appropriate to that frequency is automatically selected. The filters are located between the turret wafers C and D which serve as selector switches. The filter inputs are connected to wafer D and their outputs to wafer C. From wafer C the signal is fed via the filter C2/L1 (Board A1) and SKT3/PL3 to the RF amplifier module 1. The filter C2/L1, on board A1, functions asan image rejector.

Liguei o nanoVNA entre entrada de antena e a saida dos filtros. Com o nanoVNA Saver fiz scan aos 8 filtros, entre os 0 MHz e os 30MHz

Os filtros parecem OK.